[Crash-utility] [PATCH] Fix "vtop" command to display the swapinfo for arm64 kernel 5.19.0+

[lijiang]

Thank you for the update, Chen.
On Tue, Sep 26, 2023 at 8:44 PM Guanyou Chen <chenguanyou9338 at gmail.com>
wrote:

> arm64/pgtable: support __HAVE_ARCH_PTE_SWP_EXCLUSIVE
>
>
We can add the kernel commit to patch log as I mentioned here:
https://listman.redhat.com/archives/crash-utility/2023-September/011010.html

570ef363509b ("arm64/pgtable: support __HAVE_ARCH_PTE_SWP_EXCLUSIVE")

Otherwise, for the patch: Ack.

BTW: maybe Kazu can help improve the patch log when merging(if the patch is
also fine to him).

Thanks
Lianbo

Let's use one of the type bits: core-mm only supports 5, so there is no
> need to consume 6.
>
> Note that we might be able to reuse bit 1, but reusing bit 1 turned out
> problematic in the past for PROT_NONE handling; so let's play safe and use
> another bit.
>
> Link: https://lkml.kernel.org/r/20220329164329.208407-5-david@redhat.com
>
> Before:
> crash> vtop 70504000
> VIRTUAL     PHYSICAL
> 70504000    (not mapped)
>
> PAGE DIRECTORY: ffffff80f265c000
>    PGD: ffffff80f265c008 => 800000141537003
>    PMD: ffffff8101537c10 => 800000141538003
>    PTE: ffffff8101538820 => 12bc3e04
>
>   PTE     vtop: cannot determine swap location
>
> After:
> crash> vtop 70504000
> VIRTUAL     PHYSICAL
> 70504000    (not mapped)
>
> PAGE DIRECTORY: ffffff80f265c000
>    PGD: ffffff80f265c008 => 800000141537003
>    PMD: ffffff8101537c10 => 800000141538003
>    PTE: ffffff8101538820 => 12bc3e04
>
>   PTE                     SWAP                  OFFSET
> 12bc3e04  /first_stage_ramdisk/dev/block/zram0  1227838
>
>       VMA           START       END     FLAGS FILE
> ffffff80dfe7b578   70504000   707bd000 100073
>
> SWAP: /first_stage_ramdisk/dev/block/zram0  OFFSET: 1227838
>
> Signed-off-by: chenguanyou <chenguanyou at xiaomi.com>
> ---
>  arm64.c | 12 ++++++++++--
>  1 file changed, 10 insertions(+), 2 deletions(-)
>
> diff --git a/arm64.c b/arm64.c
> index 39d5f04..ea1b51b 100644
> --- a/arm64.c
> +++ b/arm64.c
> @@ -468,8 +468,16 @@ arm64_init(int when)
>             }
>         }
>
> -
> -       if (THIS_KERNEL_VERSION >= LINUX(4,0,0)) {
> +       if (THIS_KERNEL_VERSION >= LINUX(5,19,0)) {
> +           ms->__SWP_TYPE_BITS = 5;
> +           ms->__SWP_TYPE_SHIFT = 3;
> +           ms->__SWP_TYPE_MASK = ((1UL << ms->__SWP_TYPE_BITS) - 1);
> +           ms->__SWP_OFFSET_SHIFT = (ms->__SWP_TYPE_BITS +
> ms->__SWP_TYPE_SHIFT);
> +           ms->__SWP_OFFSET_BITS = 50;
> +           ms->__SWP_OFFSET_MASK = ((1UL << ms->__SWP_OFFSET_BITS) - 1);
> +           ms->PTE_PROT_NONE = (1UL << 58);
> +           ms->PTE_FILE = 0;  /* unused */
> +       } else if (THIS_KERNEL_VERSION >= LINUX(4,0,0)) {
>             ms->__SWP_TYPE_BITS = 6;
>             ms->__SWP_TYPE_SHIFT = 2;
>             ms->__SWP_TYPE_MASK = ((1UL << ms->__SWP_TYPE_BITS) - 1);
> --
> 2.39.0
>
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